Class PhoneticEngine

This is a two-stage process. Firstly, the word is converted into a phonetic representation that takes
into account the likely source language. Next, this phonetic representation is converted into a
pan-European 'average' representation, allowing comparison between different versions of essentially
the same word from different languages.

This class is intentionally immutable and thread-safe.
If you wish to alter the settings for a PhoneticEngine, you
must make a new one with the updated settings.